It's a phrase that's uttered too often at Little League games and on the playground. Even adults playing slow-pitch softball use it as a crutch. "You throw like a girl." It's an easy, if seemingly sexist, shorthand for the lunging, forearm focused, dart-throwing motion that happens to be one of the worst ways you can throw a baseball, softball or any other kind of ball.

In 2012, Dr. Jerry Thomas, professor of kinesiology and dean of the University of North Texas' College of Education, conducted a study try to find the basis for the stereotype in 2012, why girls do, in fact, throw worse than their male peers across all age groups.

Almost everywhere, Thomas says, the primary reason girls throw slower and shorter than boys is a lack of practice. If a male child throws poorly, his dad will help him throw better, which isn't traditionally true for girls. Thomas sought to research a culture in which this wasn't true, where girls and boys began throwing at the same age, with the same emphasis.

His search led him to work with aboriginal children in Australia, kids who grew up in a culture where everyone hunts, and throws, from childhood. Thomas found that the Australian girls threw 78.3 percent as fast as their male counterparts, a closer gap than North American, European or Asian kids, but still a significant one. Since pre-pubescent kids are about the same size regardless of sex, Thomas speculates that their may be some biological basis for the separation, a reason girls everywhere struggle with the hip, torso, arm and wrist action necessary to throw well.

"We see 3-year-olds, 3- and 4-year-olds, the boys throw better than the girls. Now, practice doesn't account for a whole lot of that when you're 3 years old. It seems to me that something besides practice and opportunity has to account for part of it," Thomas says, "but frankly, I think it's a very small part."

Bucking those odds is a small part of what makes Mo'ne Davis, the Little League World Series star from Philadelphia, so spectacular. Wednesday night, Davis experienced her first rough start of the tournament, giving up three runs on six hits in 2.1 innings before being pulled so she would still be eligible to start her team's potential U.S. Championship game on Saturday. (Davis' team was eliminated last night.)

Even in rough outing, it was easy to see why she's garnered so much media attention, including being on the cover of this week's Sports Illustrated. She struck out six and most of the damage done by her Las Vegas opponents stemmed from a couple of rally-fortifying bloop hits. The hammer curveball and 70 mph fastball were still there, getting swings and misses from a team that had averaged three runs an inning in their games prior to facing Philadelphia.

Davis is just as good, if not better, than the best of her male peers because she got the same amount of practice they did, Thomas says. At her age, there are no physical differences between Davis and the boys she so often strikes out, so she wins out because of her fluid mechanics and feel for pitching.

"That's as good a motion as you can see in a 13-year-old pitching," Thomas says. "Clearly she's practiced and that's the secret to success in any sport."

Davis' continued success depends on whether she continues to grow, according to Thomas. With her pitching skill and mechanics, her continuing to build velocity depends on the amount of leverage and arm whip she'll be able add as she gets older, which depends heavily on height. If she gets near 6 feet, Thomas says, she could develop a major league-ready fastball to complement her outstanding secondary stuff.

Mostly, Thomas hopes other girls follow Davis' lead.

"This best thing I can think of that will come out of this is girls get interested in baseball and that in future Little League World Series we have half the pitchers being girls," Thomas says. "When you see a young woman like this and you're in my field it just makes you really happy because we've promoted our whole career for equal opportunity for women in sports and we're seeing more and more of it. When you see a young woman who can perform like that it makes you really proud."